What harm was done by adding "UK" to the thread title in question?

Harm was done is this needless imposition. It may inhibit any further contributions from the poster directly affected and other posters witnessing this treatment. There is nothing friendly or welcoming about the attitude displayed and defended here.

But as has already been pointed out – the addition of UK in the context of the Licensing Act 2003 and the Government Minister responsible - is incorrect as their jurisdiction does not cover the UK. A point that would have been made by the thread's originator – had the anonymous volunteer taken the little time required to ask.
The harm done by this imposed change is that a thread title (with the originator still credited with its creation) is now knowingly incorrect – leaving the originator open to accusations of misrepresentation from Scottish posters and of not being informed.

Does it make the thread title more clear and a better index for our readers?

In fact no – this title is now incorrect and the imposition was done on this thread title - in isolation. The rights of our readers matter no more than the rights of our posters – for we are one and the same and we all should be equally respected whether posting or reading.

Does the need to preserve the sanctity of thread titles outweigh the need for clarity of indexing? Why?

No - but why do our volunteers consider the need for clarity of their indexing outweighs the need for always showing the proper respect to all the contributors they are supposed to be helping on our forum - rather than imposing their judgment upon?

What harm has ever been done by the editing done at Mudcat?

When what is imposed is plainly seen NOT to be for the reasons stated and is seen to be unfair and inconsistent as well as needlessly impolite and selectively heavy-handed – the harm done to individuals and the whole forum - is immeasurable. The imposition of the change to the second thread's title the manner in which it undertaken – is a perfect example of this harm. For if I had been asked by Joe Offer (who could have easily asked in a PM) I would have willingly agreed to a change. If folk do not know the harm done by bullying (in all its forms) they probably never will.

I feel that we have now reached the stage when a lot of these questions are for the forum to publicly debate and decide now - rather than for one individual fellow poster to now feel qualified to judge what is best for the rest of us.